One speaker was talking about big data and clinical trials. Accumulating large numbers of patient data - disease information / genetics/ treatment and response in one place will allow researchers to recognize patterns and best practices and that is a good thing.
But the session I couldn't wait to hear was Potential of Liquid Biopsies in Precision Medicine presentation by Dr Luis Diaz. I had often wondered if there was enough circulating tumor DNA (ctDNA) in the blood to measure accurately. And I wondered if you could find ctDNA from ovarian cancer tumors and maybe be able to detect ovarian cancer or a recurrence quicker.
What is a liquid biopsy? When a cancer cell dies it can shed DNA into the blood. This cell-free or circulating tumor DNA can be removed from the plasma and the genetic makeup can be studied. These DNA mutated fragments can be compared to normal alleles.
Why do a liquid biopsy? It is less invasive than a tissue biopsy. It may cost less. It may be used to follow response to treatment or signal a recurrence quicker and it can track genetic changes in the cancer.
So on Saturday afternoon, I sat in a large standing room only session to listen to Dr Diaz. During his talk Dr Diaz mentioned a pancreatic cancer study where ctDNA spiked along with the tumor marker CA19-9 showing that liquid biopsy could be used to track a recurrence. Another study (not sure of which cancer ) showed that a rising ctDNA signaled a recurrence which was confirmed by a CT scan. I was tweeting from the meeting and wanted to be sure I heard correctly when Dr Diaz mentioned that liquid biopsy could only be used for somatic mutations, so I tweeted.
And got these responsesDo I understand that Diaz said liquid biopsy only used for somatic mutations? Not Germline ? #gyncsm #ASCO16— Dee Sparacio (@womenofteal) June 4, 2016
@womenofteal liquid biopsy & tumor testing are typically optimized to find somatic mutations...germline mut. would be an unintended finding— Erica Bednar (@EMBOSU) June 4, 2016
@womenofteal Yes! Cell free DNA or circulating tumor cells are typically used for somatic while DNA from blood cells is used for germline.— Bjarne Bartlett (@BjarneBartlett) June 4, 2016
There were also other presentations/ posters on the use of liquid biopsy.
During a Tumor Biology presentation, Dr. P. Mack shared results of a study of blood samples from over 5,000 patients with 50 different tumor types (39% lung, 14% breast , 10% colon cancers) . Some of the samples were compared to patient tumor samples. The ctDNA test found mutations in 83% of the samples. And overall 87% of the ctDNA results matched the tumor samples. You may read more about this study here.
Another abstract by Dr Tie showed that the detection of ctDNA in patients with stage II colon cancer who had undergone surgery provided direct evidence of residual disease.
Circulating cell-free DNA : The future of personalized medicine in ovarian cancer management was presented as a poster. The poster reported on a study of ctDNA in the blood of 14 women with ovarian cancer. The tumor tissue of the women underwent next-generation sequencing. The researchers found that ctDNA detected more mutations than what was found in the solid tumors. (poster abstract.).
A number of companies (including Guardant Health which was used in the Mack study) have introduced liquid biopsy equipment.
I look forward to the application of ct DNA in future ovarian cancer research/ treatment.
Dee
Every Day is a Blessing!
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